FIG. 1 is a view illustrating an installation condition of a typical infusion solution set, and FIG. 2 is a view illustrating various types of infusion solution flow rate controllers for controlling the flow rate of infusion solution in a commercially available infusion solution.
Treatment using an infusion solution is carried out by connecting an infusion solution bottle 1 to an infusion solution set 2 and applying the water pressure coming from the difference in height between the infusion solution bottle 1 and the injection needle 30 to administer the infusion solution contained in the infusion solution bottle 1 to the patient through the injection needle 30 of the infusion solution 2.
The infusion solution set 2 connected with the infusion solution bottle 1 includes a insertion needle 11 at an upper portion thereof, which is inserted through the sealing cap of the infusion solution bottle 1 to allow the infusion solution to flow out of the infusion solution bottle 1, a dropping container 10 allowing the infusion solution flowing out through the insertion needle 11 to drop to an inner space thereof in the form of drops (unit: gtt) to collect in a lower portion of the inner space and then discharge, the injection needle 30 inserted into the patient's vein, a tube 20 connecting the dropping container 10 with the insertion needle 30 and functioning as a pathway for injecting the infusion solution, and an infusion solution flow rate controller 40 and roller clamp 40′ provided at a middle of the tube 20 to control the flow rate of infusion solution.
The drop 12 falls in the inside of the dropping container 10 in the form of a water drop. The dropping container 10 is manufactured to have a predetermined volume as possible. For example, when manufactured to discharge 20 drops per 1 cc of infusion solution, the volume of one drop is 1/20 cc, and when manufactured to discharge 60 drops per 1 cc of infusion solution, the volume of one drop is 1/60 cc. Accordingly, the flow rate of infusion solution injected through the infusion solution set 2 may be calculated by measuring the period at which the drop falls inside the dropping container 10.
A target flow rate prescribed in an actual clinic may be adjusted by measuring the number of drops considering all other factors (height or type of infusion solution, thickness of injection needle, patient vascular resistance, etc.) than the infusion solution flow rate controller and positioning the flow rate controlling means based on the measured number.
Here, as the flow rate controlling means installed in the infusion solution set, there are the roller clamp 40′ and the infusion solution flow rate controller 40 according to the shape of the adjusting part and the principle of controlling flow rate. The roller clamp 40′ varies the cross-sectional area of flow path of the tube 20 by moving up and down a manipulating unit 41′ constituted of rollers. The roller clamp 40′ determines the maximum and minimum speed by a small degree of spacing control and thus has difficulty in controlling and marking exact gradations.
In order to compensate for such shortcomings of the roller clamp 40′, the infusion solution flow rate controller 40 (also referred to as an IV flow regulator) has been recently developed that controls the flow rate by varying internal flow paths as shown in FIG. 1 or 2. The infusion solution flow rate controller 40 may vary flowrates by rotating the manipulating unit 41 to change rotation angles. The infusion solution flow rate controller 40 has display gradations 42 marked within a rotation angle adjustment range and may be adjusted to a display gradation 42 fitting the target flow rate to adjust the flow rate.
As shown in FIG. 1, the infusion solution set with the infusion solution flow rate controller 40 generally uses the roller clamp 40′ as well.
In the clinic, however, the flow rate of infusion solution administered and measured by the infusion solution set 2 shows a substantial difference from the display gradation 42. This is why the display gradation 42 of the infusion solution flow rate controller 40 has been marked based on the result obtained by performing a test using one type of infusion solution at a predetermined height in the lab without considering factors actually influencing the speed of infusion solution (e.g., height or type of infusion solution, thickness of injection needle, and patient's vascular resistance). The actual clinical site reveals significant differences from the lab. Most of all, since the lab does not consider the patient's vascular resistance (which varies for each of children, young people, or elderly people), prescribing the speed depending on the speed displayed is very critical in treating the patient, and a significant difference between prescribed flow rate and actually administered flow rate may put the patient in high risk.
According to Applicant's Korean Patent No. 10-1058539, a reference point is set when marking a display gradation 42 in an infusion solution flow rate controller 40, and a relative ratio between the flow rate at the display gradation and the flow rate at the reference point is marked as a display gradation so that a target flow rate of infusion solution may be administered only by measuring the flow rate at the reference point and then adjusting to the display gradation fitting the ratio with the target flow rate. According to this, since the target flow rate may be adjusted by the flow rate actually measured only once, the display gradation fitting the target flow rate may be quickly discovered.
However, currently available infusion solution flow rate controllers adjust the flow rate by varying the depth of circular flow path, so that the flow pattern according to the variation in display gradation is not linear.
In Korean Patent No. 10-1058539, the infusion solution flow rate controller needs to be a linear system in order to display gradations of the infusion solution flow rate controller with relative ratios, and this is pricey and pose limitations on commercial use.
Further, since the display gradations of the infusion solution flow rate controller are marked with ratios upon correction speed, the reference point of the infusion solution flow rate controller should always be fixed at the same position when measuring the flow rate once in order to discover a display gradation fitting the target flow rate, and the position of the flow rate controller should be moved back to the reference point even upon speed correction during the infusion solution treatment.
Further, since the speeds are indicated with ratios, it differs from the actual display unit gradation that is conventionally used and thus leads to difficulties in intuitive use and changing custom.